spark执行器看不到隐式值(java.lang.nullpointerexception)

f3temu5u  于 2021-05-27  发布在  Spark
关注(0)|答案(1)|浏览(409)

我有一个Spark应用程序，我不能开始在纱。我得到空指针异常(上主本地应用程序（工作良好）。我的应用程序正在将嵌套的xml转换为json。
我正在将xmls加载到rdd中： val xml_rdd = spark.sparkContext.textFile(path) 我正在将xmls转换为json scala.xml.XML.loadString(xmlStr).toJson.toString() . toJson 方法需要隐式writer，因此我正在创建它：

implicit val writer: JsonWriter[Elem]  = new JsonWriter[Elem] {
    def write(elem: Elem): JsValue = {
        ...
    }
}

完整代码：

import com.typesafe.scalalogging.LazyLogging
import org.apache.spark.sql.SparkSession
import spray.json.{JsArray, JsObject, JsString, JsValue, JsonWriter, _}

import scala.xml._

object Test  extends  App with LazyLogging{

    val in_path = args(0)
    val spark: SparkSession = SparkSession.builder().appName(this.getClass.getSimpleName).getOrCreate()
    val xml_rdd = spark.sparkContext.textFile(in_path)

    implicit val writer: JsonWriter[Elem]  = new JsonWriter[Elem] {
        def write(elem: Elem): JsValue = {
            if (List("Persons").contains(elem.label)) {
                JsArray(
                    elem.child.collect {
                        case e: Elem => write(e)
                    }: _*)
            } else if (elem.child.isEmpty) {
                JsString("")
            } else if (elem.child.count(_.isInstanceOf[Text]) == 1){
                JsString(elem.text)
            } else
                JsObject(
                    elem.child.collect {
                        case e: Elem => e.label -> write(e)
                    }: _*)
        }
    }
    val json_rdd = xml_rdd.map(xmlStr => scala.xml.XML.loadString(xmlStr).toJson.toString())

    json_rdd.collect().foreach(println)
}

我的调试表明这个问题已经解决了 toJson 方法。似乎隐写器只存在于驱动程序上，执行者看不到它。我试过广播 writer 为了向遗嘱执行人提供 spark.sparkContext.broadcast(jsonSerializer) 但随后我收到了object not serializable异常。
你能帮我在遗嘱执行人身上做些什么吗？或者告诉我我犯了什么错误？
完全堆栈跟踪异常：

20/05/28 12:45:25 INFO scheduler.DAGScheduler: ResultStage 0 (collect at Test.scala:36) failed in 3.992 s due to Job aborted due to stage failure: Task 1 in stage 0.0 failed 4 times, most recent failure: Lost task 1.3 in stage 0.0 (TID 8, something.bla, executor 5): java.lang.NullPointerException
        at spray.json.RichAny.toJson(package.scala:44)
        at com.something.Test$$anonfun$1.apply(Test.scala:34)
        at com.something.Test$$anonfun$1.apply(Test.scala:34)
        at scala.collection.Iterator$$anon$11.next(Iterator.scala:410)
        at scala.collection.Iterator$class.foreach(Iterator.scala:891)
        at scala.collection.AbstractIterator.foreach(Iterator.scala:1334)
        at scala.collection.generic.Growable$class.$plus$plus$eq(Growable.scala:59)
        at scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:104)
        at scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:48)
        at scala.collection.TraversableOnce$class.to(TraversableOnce.scala:310)
        at scala.collection.AbstractIterator.to(Iterator.scala:1334)
        at scala.collection.TraversableOnce$class.toBuffer(TraversableOnce.scala:302)
        at scala.collection.AbstractIterator.toBuffer(Iterator.scala:1334)
        at scala.collection.TraversableOnce$class.toArray(TraversableOnce.scala:289)
        at scala.collection.AbstractIterator.toArray(Iterator.scala:1334)
        at org.apache.spark.rdd.RDD$$anonfun$collect$1$$anonfun$13.apply(RDD.scala:945)
        at org.apache.spark.rdd.RDD$$anonfun$collect$1$$anonfun$13.apply(RDD.scala:945)
        at org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:2101)
        at org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:2101)
        at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:90)
        at org.apache.spark.scheduler.Task.run(Task.scala:121)
        at org.apache.spark.executor.Executor$TaskRunner$$anonfun$10.apply(Executor.scala:408)
        at org.apache.spark.util.Utils$.tryWithSafeFinally(Utils.scala:1360)
        at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:414)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)

Driver stacktrace:
20/05/28 12:45:25 INFO scheduler.DAGScheduler: Job 0 failed: collect at Test.scala:36, took 4.031537 s
Exception in thread "main" org.apache.spark.SparkException: Job aborted due to stage failure: Task 1 in stage 0.0 failed 4 times, most recent failure: Lost task 1.3 in stage 0.0 (TID 8, something.bla, executor 5): java.lang.NullPointerException
        at spray.json.RichAny.toJson(package.scala:44)
        at com.something.Test$$anonfun$1.apply(Test.scala:34)
        at com.something.Test$$anonfun$1.apply(Test.scala:34)
        at scala.collection.Iterator$$anon$11.next(Iterator.scala:410)
        at scala.collection.Iterator$class.foreach(Iterator.scala:891)
        at scala.collection.AbstractIterator.foreach(Iterator.scala:1334)
        at scala.collection.generic.Growable$class.$plus$plus$eq(Growable.scala:59)
        at scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:104)
        at scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:48)
        at scala.collection.TraversableOnce$class.to(TraversableOnce.scala:310)
        at scala.collection.AbstractIterator.to(Iterator.scala:1334)
        at scala.collection.TraversableOnce$class.toBuffer(TraversableOnce.scala:302)
        at scala.collection.AbstractIterator.toBuffer(Iterator.scala:1334)
        at scala.collection.TraversableOnce$class.toArray(TraversableOnce.scala:289)
        at scala.collection.AbstractIterator.toArray(Iterator.scala:1334)
        at org.apache.spark.rdd.RDD$$anonfun$collect$1$$anonfun$13.apply(RDD.scala:945)
        at org.apache.spark.rdd.RDD$$anonfun$collect$1$$anonfun$13.apply(RDD.scala:945)
        at org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:2101)
        at org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:2101)
        at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:90)
        at org.apache.spark.scheduler.Task.run(Task.scala:121)
        at org.apache.spark.executor.Executor$TaskRunner$$anonfun$10.apply(Executor.scala:408)
        at org.apache.spark.util.Utils$.tryWithSafeFinally(Utils.scala:1360)
        at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:414)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)

Driver stacktrace:
        at org.apache.spark.scheduler.DAGScheduler.org$apache$spark$scheduler$DAGScheduler$$failJobAndIndependentStages(DAGScheduler.scala:1889)
        at org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:1877)
        at org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:1876)
        at scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59)
        at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:48)
        at org.apache.spark.scheduler.DAGScheduler.abortStage(DAGScheduler.scala:1876)
        at org.apache.spark.scheduler.DAGScheduler$$anonfun$handleTaskSetFailed$1.apply(DAGScheduler.scala:926)
        at org.apache.spark.scheduler.DAGScheduler$$anonfun$handleTaskSetFailed$1.apply(DAGScheduler.scala:926)
        at scala.Option.foreach(Option.scala:257)
        at org.apache.spark.scheduler.DAGScheduler.handleTaskSetFailed(DAGScheduler.scala:926)
        at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.doOnReceive(DAGScheduler.scala:2110)
        at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:2059)
        at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:2048)
        at org.apache.spark.util.EventLoop$$anon$1.run(EventLoop.scala:49)
        at org.apache.spark.scheduler.DAGScheduler.runJob(DAGScheduler.scala:737)
        at org.apache.spark.SparkContext.runJob(SparkContext.scala:2061)
        at org.apache.spark.SparkContext.runJob(SparkContext.scala:2082)
        at org.apache.spark.SparkContext.runJob(SparkContext.scala:2101)
        at org.apache.spark.SparkContext.runJob(SparkContext.scala:2126)
        at org.apache.spark.rdd.RDD$$anonfun$collect$1.apply(RDD.scala:945)
        at org.apache.spark.rdd.RDDOperationScope$.withScope(RDDOperationScope.scala:151)
        at org.apache.spark.rdd.RDDOperationScope$.withScope(RDDOperationScope.scala:112)
        at org.apache.spark.rdd.RDD.withScope(RDD.scala:363)
        at org.apache.spark.rdd.RDD.collect(RDD.scala:944)
        at com.something.Test$.delayedEndpoint$com.something$Test$1(Test.scala:36)
        at com.something.Test$delayedInit$body.apply(Test.scala:10)
        at scala.Function0$class.apply$mcV$sp(Function0.scala:34)
        at scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:12)
        at scala.App$$anonfun$main$1.apply(App.scala:76)
        at scala.App$$anonfun$main$1.apply(App.scala:76)
        at scala.collection.immutable.List.foreach(List.scala:392)
        at scala.collection.generic.TraversableForwarder$class.foreach(TraversableForwarder.scala:35)
        at scala.App$class.main(App.scala:76)
        at com.something.Test$.main(Test.scala:10)
        at com.something.Test.main(Test.scala)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.apache.spark.deploy.JavaMainApplication.start(SparkApplication.scala:52)
        at org.apache.spark.deploy.SparkSubmit.org$apache$spark$deploy$SparkSubmit$$runMain(SparkSubmit.scala:849)
        at org.apache.spark.deploy.SparkSubmit.doRunMain$1(SparkSubmit.scala:167)
        at org.apache.spark.deploy.SparkSubmit.submit(SparkSubmit.scala:195)
        at org.apache.spark.deploy.SparkSubmit.doSubmit(SparkSubmit.scala:86)
        at org.apache.spark.deploy.SparkSubmit$$anon$2.doSubmit(SparkSubmit.scala:924)
        at org.apache.spark.deploy.SparkSubmit$.main(SparkSubmit.scala:933)
        at org.apache.spark.deploy.SparkSubmit.main(SparkSubmit.scala)
Caused by: java.lang.NullPointerException
        at spray.json.RichAny.toJson(package.scala:44)
        at com.something.Test$$anonfun$1.apply(Test.scala:34)
        at com.something.Test$$anonfun$1.apply(Test.scala:34)
        at scala.collection.Iterator$$anon$11.next(Iterator.scala:410)
        at scala.collection.Iterator$class.foreach(Iterator.scala:891)
        at scala.collection.AbstractIterator.foreach(Iterator.scala:1334)
        at scala.collection.generic.Growable$class.$plus$plus$eq(Growable.scala:59)
        at scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:104)
        at scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:48)
        at scala.collection.TraversableOnce$class.to(TraversableOnce.scala:310)
        at scala.collection.AbstractIterator.to(Iterator.scala:1334)
        at scala.collection.TraversableOnce$class.toBuffer(TraversableOnce.scala:302)
        at scala.collection.AbstractIterator.toBuffer(Iterator.scala:1334)
        at scala.collection.TraversableOnce$class.toArray(TraversableOnce.scala:289)
        at scala.collection.AbstractIterator.toArray(Iterator.scala:1334)
        at org.apache.spark.rdd.RDD$$anonfun$collect$1$$anonfun$13.apply(RDD.scala:945)
        at org.apache.spark.rdd.RDD$$anonfun$collect$1$$anonfun$13.apply(RDD.scala:945)
        at org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:2101)
        at org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:2101)
        at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:90)
        at org.apache.spark.scheduler.Task.run(Task.scala:121)
        at org.apache.spark.executor.Executor$TaskRunner$$anonfun$10.apply(Executor.scala:408)
        at org.apache.spark.util.Utils$.tryWithSafeFinally(Utils.scala:1360)
        at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:414)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)
yarnscalarddapache-sparkimplicit

1条答案

按热度按时间
mfuanj7w

mfuanj7w1#

通常在每个执行器上创建不可序列化的内容。e、 g.考虑以下示例：

// this fails when you call an "action" on myrdd2
val myNonSerializableObj = new Thread();
val myrdd2 = myrdd.map( elem => myNonSerializableObj.toString() + "-" + elem )

// this works
val myrdd3 = myrdd.mapPartitions{ partition =>
  val myNonSerializableObj = new Thread();
  partition.map{ elem =>
    myNonSerializableObj.toString() + "-" + elem
  }
}
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